Arc welding system



March '13, 1928. 1362369 J. KJEKSTAD ARC WELDING SYSTEM Filed Aug. 1, 1918 WITNESS:

- I INVENTOR. W- 7942M;

A TTORNEYS Patented Mar. 13, 1928.

UNITED STATES PATENT ()FFlCE.

JOHANNES KJE KSTAD, OF BROOKLYN, NEW YORK, ASSIGNOR OF ONE-HALF TO WILLIAM SCHENSTBOM, OF BROOKLYN, NEW YORK.

ARC WELDING SYSTEM.

My invention relates to electric arc weld ing and is broadly applicable to both carbon arc welding in which the work constitutes one electrode and a carbon rod or pencil constitutes the other electrode, and to metallic arc welding in which one electrode is a metallic rod or pencil which is consumed and deposited by the are u on the other electrodeor work to be wel ed.

It is important that the character of the weld be as uniform as possible throughout. In carbon arc welding it is therefore important that the line of weld be evenly heated which requires that the rate of travel of the are along the work be commensurate with the heat of the arc. Also it is a desideratum in metallic arc welding to obtain a' uniform deposit or string of the metal along the line ofweld. Since in the latter casethe rate at which metal is being deposited seems to increase with the temperature of'the arc, it-becomes a common requisite for both kinds of electric welding that the are be moved at a rate commensurate with its temperature. T

The temperature of the arc is determined by the proportion between the rate at which heat is being produced in the arc and the rate at which it is being dissipated, the heat production increasing with the Watt consumption; i. e., the product of amperage and the voltage across the arc, and the dissipation with the length of the arc.

:A change in arc length will also directly afieot the watt consumption. Thus, if the arc is fed from a source of constant voltage, an increase in its length will also increase its resistance, causing the voltage across the arc to rise and the amperage to drop, giving a new value for the watt consumption.

Apparently the proportion between watt consumption and heat dissipation: i. e., the temperature, decreases with a lengthening of the are because it. results in a falling oil of the rate at which the electrode is consumed.

In practice it is impossible to maintain the length of an are constant. For instance, in the manual operation of welding, the natural unsteadiness of the hand causes the arc. and hence its temperature, to vary; to insure a uniform weld the rate of movement of the are along the weld would have to be varied accordingly, but this is manifestly an accomplishment equally impossible of attainment in manual operation.

An object of my invention is to provide Application filed August 1, 1918. Serial No. 247,734.

means for automatically regulating the movement of the arc. across the work and thereby in carbon arc welding. obtain a substantially uniform heating alongthe line of the weld, and in metallic arc welding obtain a uniform string irrespective'of variations'in the arc.

This is accomplished, in accordance with my invention, by providing a carriage for one of the electrodes and an automatic feeding device for the carriage, and automatically regulating the feed of the device by the arc. Preferably the device is an electromagnetic device responsive to variations in resistance across the arc.

My invention also comprehends various otherfeatures of construction and arrangements 0t parts, as will hereinafter more fully appear.

I shall now describe the illustrated embodiment of my invention and shall thereafter point out my invention in claims.

Fig. l is a schematic view of one e1nbodiment of my invention; and

Fig. 2 is a diagrammatic view of a modification ot' the same.

For purposes of illustration the electrode 1 is assumed to be a metallic electrode, and is shown as provided with a handle for manual control of the length of the arc, although it will be understood that any suit able automatic device could be employed for that purpose. Inorder to cause the arc to travel along the seam or line of weld of the work 2, either the electrode 1 or the work 2 is translated. In the illustrated embodiment the work is shown as mounted upon a table 3 which is translated by gearing 4icooperating with a rack 5 on the under side of the table. An electric motor M in Figure 1 is arranged in series with the are and communicates power to the gearing 4 through suitable reduction gearing 6. Current is supplied from a generator G.

To initiate the operation the operator closes the switch 7 and momentarily brings the electrode 1 into contact with the work 2 at the beginning of line of weld and then withdraws theelectrode sufiiciently to strike an are. In order to hold the electrode 1 steady in the line of its axis and prevent any lateral movement thereof, a suitable guide 8 may be employed in manual. as well as automatic control of the electrode. The motor M promptly starts to feed the table along at a rate dependent upon the current. The shorter the arc the higher the amperage and also the faster the rate of deposit of the metal upon the Work, and vice versa. Therefore the rate of feed of the table is dependent upon the length of the arc, and the result is that the table is fed substantially in proportion to the rate of deposit of the metal.

The same result may also be obtained in other ways. F or instance, as shown in Figure 2, the motor M may have its field connccted in shunt with the arc, and as a consequence of the field strength varying inversely with the amperage at the arc, the motor will accelerate with a decrease in the length of the arc. and vice versa.

It is obvious that various modifications may be made in the constructions shown in the drawings and above particularly described Within the principle and scope of my invention.

I claim:

1. An electric arc welding system comprising the combination with the Work and an electrode arranged to have an arc estab noeaaoa lished between them, of an electric motor operative to translate the electrode relative to the Work and so arranged in the electric circuit that it will accelerate on a decrease in the length of the arc and decelerate on an increase in the length of thearc.

2. An electric arc Welding system comprising an electric circuit including the work and an electrode arranged to have an are established betweenitselt and the Work, a movable support for the Work, a source of current for said circuit and an electric motor disposed in said circuit and operative to move the support and responsive to variations in resistance across the are.

3. An arc Welding machine, comprising a fusible electrode cooperating With the WEltling joint to strike an are at said joint, means for progressively presenting said joint to said electrode, and means controlled by voltage variations in said are for controlling the speed of progression of said joint.

in Witness whereohl suhscrlbe my signature,

J QHANNES KJEKSTAD. 

